This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

LM5122-Q1: Slope Compensation resistor

Guru 20090 points
Part Number: LM5122-Q1
Other Parts Discussed in Thread: LM5122

Hello,

If we use a value for slope compensation lower than the calculated value, I think that Vslope will be larger than the voltage actually required.
In this case, what kind of behavior are you concerned about?

The inductance for boost dc/dc of the LM5122 is 2.6uH.
However, there is also a 5.6 uH inductor on the battery input side as a filter in the customer.
The value of Rslope differs depending on calculation at 2.6 uH and 8.2 uH, but they use the value calculated at 2.6 uH.
Therefore, it is smaller than Rslope calculated at 8.2 uH.
Is there any concern that sub harmonic oscillation will occur in this case?

Best Regards,
RYuji

  • Hello

    If the Rslope value is too small, there is a possibility that COMP is saturated at heavy load. If the Rslope value is too big, there can be a sub harmonic oscillation as you mentioned.  Please refer the section 8.2.2.6 in the datasheet.

    Thanks